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The Evolution of the Baryons Associated with Galaxies Averaged over Cosmic Time and Space

Walter, Fabian; Carilli, Chris; Neeleman, Marcel; Decarli, Roberto; Popping, Gergö; Somerville, Rachel S.; Aravena, Manuel; Bertoldi, Frank; Boogaard, Leindert; Cox, Pierre; da Cunha, Elisabete; Magnelli, Benjamin; Obreschkow, Danail; Riechers, Dominik; Rix, Hans-Walter; Smail, Ian; Weiss, Axel; Assef, Roberto J.; Bauer, Franz; Bouwens, Rychard; Contini, Thierry; Cortes, Paulo C.; Daddi, Emanuele; Diaz-Santos, Tanio; González-López, Jorge; Hennawi, Joseph; Hodge, Jacqueline A.; Inami, Hanae; Ivison, Rob; Oesch, Pascal; Sargent, Mark; van der Werf, Paul; Wagg, Jeff; Yung, L.Y. Aaron

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Authors

Fabian Walter

Chris Carilli

Marcel Neeleman

Roberto Decarli

Gergö Popping

Rachel S. Somerville

Manuel Aravena

Frank Bertoldi

Leindert Boogaard

Pierre Cox

Elisabete da Cunha

Benjamin Magnelli

Danail Obreschkow

Dominik Riechers

Hans-Walter Rix

Axel Weiss

Roberto J. Assef

Franz Bauer

Rychard Bouwens

Thierry Contini

Paulo C. Cortes

Emanuele Daddi

Tanio Diaz-Santos

Jorge González-López

Joseph Hennawi

Jacqueline A. Hodge

Hanae Inami

Rob Ivison

Pascal Oesch

Mark Sargent

Paul van der Werf

Jeff Wagg

L.Y. Aaron Yung



Abstract

We combine the recent determination of the evolution of the cosmic density of molecular gas (H2) using deep, volumetric surveys, with previous estimates of the cosmic density of stellar mass, star formation rate and atomic gas (H i), to constrain the evolution of baryons associated with galaxies averaged over cosmic time and space. The cosmic H i and H2 densities are roughly equal at z ~ 1.5. The H2 density then decreases by a factor ${6}_{-2}^{+3}$ to today's value, whereas the H i density stays approximately constant. The stellar mass density is increasing continuously with time and surpasses that of the total gas density (H i and H2) at redshift z ~ 1.5. The growth in stellar mass cannot be accounted for by the decrease in cosmic H2 density, necessitating significant accretion of additional gas onto galaxies. With the new H2 constraints, we postulate and put observational constraints on a two-step gas accretion process: (i) a net infall of ionized gas from the intergalactic/circumgalactic medium to refuel the extended H i reservoirs, and (ii) a net inflow of H i and subsequent conversion to H2 in the galaxy centers. Both the infall and inflow rate densities have decreased by almost an order of magnitude since z ~ 2. Assuming that the current trends continue, the cosmic molecular gas density will further decrease by about a factor of two over the next 5 Gyr, the stellar mass will increase by approximately 10%, and cosmic star formation activity will decline steadily toward zero, as the gas infall and accretion shut down.

Citation

Walter, F., Carilli, C., Neeleman, M., Decarli, R., Popping, G., Somerville, R. S., …Yung, L. A. (2020). The Evolution of the Baryons Associated with Galaxies Averaged over Cosmic Time and Space. Astrophysical Journal, 902(2), Article 111. https://doi.org/10.3847/1538-4357/abb82e

Journal Article Type Article
Acceptance Date Aug 13, 2020
Online Publication Date Sep 19, 2020
Publication Date 2020-10
Deposit Date Nov 17, 2020
Publicly Available Date Mar 29, 2024
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 902
Issue 2
Article Number 111
DOI https://doi.org/10.3847/1538-4357/abb82e

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
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of the Creative Commons Attribution 4.0 licence. Any further
distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.





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